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