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