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