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