One vertex per element, one color per generator, with an edge from x to x·s.
(10,11)(15,17)(16,18)(22,23)(27,34)(29,32)(35,40)(37,39) involution — undirected(1,2)(3,7)(4,5)(6,8)(9,10,14,11)(12,17,20,15)(13,16,21,18)(19,23,24,22)(25,26,31,30)(27,32,34,29)(28,36,38,33)(35,37,40,39)(2,5)(6,7)(13,21)(16,18)(19,24)(22,23)(25,27,31,34)(26,32,30,29)(28,35,38,40)(33,39,36,37)(9,11,14,10)(12,17,20,15)(13,18,21,16)(19,23,24,22)(25,28,31,38)(26,33,30,36)(27,35,34,40)(29,37,32,39)(1,3,4,8)(2,6,5,7)(9,12)(10,15)(11,17)(13,19)(14,20)(16,22)(18,23)(21,24)(25,29)(26,27)(28,37)(30,34)(31,32)(33,35)(36,40)(38,39)(1,2)(3,6)(4,5)(7,8)(9,13,14,21)(10,16,11,18)(12,19,20,24)(15,22,17,23)(25,30,31,26)(27,29,34,32)(28,36,38,33)(35,37,40,39)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.