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