One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,5,7,8)(9,10)(11,17)(12,18)(13,16)(14,15)(19,23)(20,24)(21,22)(26,30)(27,33)(32,38)(35,36)(1,3,4,7)(2,5,6,8)(10,15)(11,18)(16,22)(19,24)(25,26,29,30)(27,34,33,31)(28,32,37,38)(35,40,36,39)(1,2)(3,5)(4,6)(7,8)(9,11)(10,12)(13,19)(14,18)(15,17)(16,20)(21,24)(22,23)(25,26,29,30)(27,31,33,34)(28,32,37,38)(35,39,36,40)(1,3)(2,5)(4,7)(6,8)(9,11)(10,12)(13,19)(14,18)(15,17)(16,20)(21,24)(22,23)(25,27)(26,31)(28,36)(29,33)(30,34)(32,40)(35,37)(38,39) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,12)(10,11)(13,20)(14,17)(15,18)(16,19)(21,23)(22,24)(25,26)(27,31)(28,32)(29,30)(33,34)(35,39)(36,40)(37,38) involution — undirected(9,13,14,21)(10,16,15,22)(11,19,18,24)(12,20,17,23)(25,28,29,37)(26,32,30,38)(27,35,33,36)(31,39,34,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.