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