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