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