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