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