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