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