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