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