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