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