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